I'm back with my dual 3.5" speaker brackets

I may order one of these real soon for my 72 Duster, I have Kenwood 3-way 6x9's in the rear speaker shelf and I'm gonna order a Kenwood KDC152 receiver since they're cheap on ebay.

What are you guys doing for additional speakers, are you putting round speakers in the doors, or maybe in the kick panels? I'm thinking the 2 6x9's and the 2 small dash speakers aren't gonna be enough. I don't plan on any amps or subwoofers for this particular car.